“Smart” weapons, also referred to as precision guided munitions (PGMs), alter their trajectories in flight to seek, or home on, their targets. Unlike conventional ballistic munitions, their accuracy does not normally diminish as range increases. Generally speaking, smart weapons are divided into four categories, according to their method of homing: command guidance, active, semiactive, and passive. Munitions using command guidance are steered to the target by a remote system or operator that performs all target acquisition, tracking, and guidance functions. Active systems home on their targets using emissions transmitted by the munition itself. Semiactive smart weapons home on energy bounded off the target by an external transmitter, usually aboard the launch platform. Passive systems home on energy emitted by the target.
Some smart weapons do not fit cleanly in the above typology. For example, the Tomahawk missile does not actually home on the target but uses on-board radar to generate midcourse guidance corrections for its inertial navigation system. ALCM missiles fly to a precise set of coordinates using an inertial guidance system updated by Global Positioning System satellite transmissions.
Newly produced tactical aircraft are designed to carry and deploy such smart weapons. This, for example, has led to a dramatic reduction in the collateral damage associated with conventional “dumb bombs”. The smart weapons typically are secured on a bomb rack which is mounted either in a bomb bay or to pylons under the wing of the aircraft. An electrical cable, known as an “umbilical cable”, couples the aircraft to a respective smart weapon on the bomb rack. The umbilical cable typically runs from the bomb bay support structure or pylon to the smart weapon itself.
The umbilical cable serves as an electrical connection for delivering power and exchanging data between the aircraft and the smart weapon. The smart weapons typically are designed to accept power, data and control information from the aircraft in order to carry out operations. The aircraft, on the other hand, are designed to provide the appropriate power, data and control information to the umbilical cable via the pylon.
For example, newly produced tactical aircraft are internally wired with the MIL-STD-1553 databus for coupling to the MIL-STD-1760 standard weapons interface. Smart weapons such as the Joint Direct Attack Munition (JDAM) are designed to communicate with the aircraft via such interface to obtain information from the aircraft such as coordinate data, etc., in order to carry out operations.
Unfortunately, there is a significant number of older aircraft that are still in use today but are not properly equipped to handle smart weapons. For example, such aircraft may not include the MIL-STD-1553 databus and thus are unable to communicate with a smart weapon such as the JDAM. Replacing the older aircraft, which are otherwise perfectly functional, is extremely expensive considering the cost of modern military aircraft. However, even retrofitting an older aircraft to include the necessary wiring (e.g., databus) and sophisticated avionics to provide the necessary information to a smart weapon is very costly. Consequently, many older aircraft today remain unable to handle smart weapons and therefore their operators cannot make use of the advantages associated therewith.
In view of the aforementioned shortcomings, there remains a strong need in the art for means to enable aircraft not equipped to handle smart weapons to nevertheless do so.